Certain houses give hope to us all. This two-story, shingle-sided ranch on a creek off the Long Island Sound started out life, probably in the 1950s, as a modest contractor’s special. It was built before credit cards, when money and materials were scarce and bank loans stingy. Then, probably in the 1960s, the house in Sag Harbor, New York, was expanded, still modestly, with an extension on one end. A decade or two later, more ambitiously, the then-owners hired an architect to break open the bungalow with an addition that transformed the box.
That flat-roofed addition, with a combined living and dining room above and playroom below, was built perpendicular to the rectangular house. The house was no longer small, but it wasn’t quite large, either—between 3,500 and 4,000 square…
